The art of secured environments developed as a result of two basic requirements. First is the requirement of physical security, and second is the requirement of electronic security. Physical security for work areas is, of course, an old art and includes a wide variety of apparatus, from the known locked dor to sophisticated alarm systems. Electronic security deals with the prevention of surrepetitious detection by electronic means of confidential information.
It is known to provide apparatus for an individual to perform such functions as letter writing or speaking on the telephone from a single location. For example, a desk in an office is such an apparatus. The known roll-top desk includes a top for physical security which is placed in one position to allow the use of a horizontal surface of the desk. After use, the top is placed over the horizontal surface and locked to prevent unauthorized access to materials on the desk.
While only physical security was adequate for many years to prevent surreptitious detection of information, development of electronic devices has required other techniques for preventing unauthorized access to materials contained on a desk or transmitted electronically from the desk. For example, if an electronic device, such as a word processor, is operated, it may be possible to detect information contained in the word processor in various ways. First, it is possible to breach physical security and simply remove the memory elements of the word processor. Second, the word processor emanates electromagnetic waves, and it may be possible to detect those waves by the use of sophisticated electronic equipment.
It is known to electronically shield a device such as a word processor to limit the emanation of electromagnetic waves and to reduce the detectable characteristics of these waves to an acceptable level. This acceptable level is determined by the state of the art in electronic eavesdropping devices and other factors. In the United States, a common standard for providing electronic security for a single piece of electronic equipment is the "Tempest" standard.
While the shielding of electronic apparatus substantially reduces the possibility of surreptitious detection of emanated electromagnetic waves, it cannot entirely prevent it. Thus, it is not possible to place even a shielded piece of equipment in an arbitrary location in a room. The room must first be analyzed in what is known as a "site survey" to determine an acceptable location for the electronic apparatus. This site survey is unique for each room and requires a highly-trained person to inspect and analyze each proposed location.
Another complicating factor in the art of secured environments is the desire to transmit electronic signals to a remote location. These signals may contain data which is desired to be maintained in secrecy. The utility of direct detection of the electronic signal is typically eliminated by encoding the data with an encryption device. The encryption device codes the outgoing data in a manner which is known only to an authorized recipient. In a typical combination, a word processor is electronically connected to an encryption device which then transmits coded signals over a telephone line to the recipient.
Transmission of the information over the telephone line is accomplished with a modulator-demodulator (MODEM). The output from the encryption device is connected to the MODEM, and the MODEM in turn transmits the coded signals over the telephone lines.
This transmission of signals, however, is not entirely free from detection since it is possible for uncoded information to be superimposed on the encoded signal because of an electronic coupling between the word processor and the output line from the encryption device. If this occurs, the MODEM simply transmits both the coded and uncoded information over the telephone lines. An unauthorized person can then directly detect the combined signals and separate the uncoded data from the coded data by appropriate filtering.
The possibility of coupling between a word processor and a MODEM is reduced by using shielded conductors to connect these pieces of equipment. Also, the MODEM may electronically couple directly to the word processor, and this is usually prevented by placing the MODEM a substantial distance from the word processor and from the encryption device.
The major difficulty with the prior art procedure is that it takes a substantial amount of time to conduct the site survey and to make necessary modifications in the room. For example, one must determine all of the dimensions of the room, the make-up of the walls of the room and the identity of the neighbors. If it is necessary to modify the room by moving a wall in order to obtain adequate distance between pieces of equipment or by adding shielded conduit, additional expense is incurred. Further, it is usually specified that a particular organization, such as the U.S. Army Corps of Engineers, be employed to make the necessary physical changes, thus resulting in time lost in scheduling, etc.
This prior procedure is extremely time consuming and results in the inability to quickly set up a new installation.
The patent literature shows various techniques for dealing with physical security. The art does not, however, provide a workable combination of electronic security and physical security.
U.S. Pat. No. 4,167,298 (Plattner) simply shows a cabinet having a door which is pivoted to permit access to the cabinet; U.S. Pat. No. 4,128,285 (Lore, et al.) shows a work table wherein a theft-proof cover includes several sections connected to each other by hinges, and the cover may then be folded when the work station is in use; U.S. Pat. No. 4,066,305 (Gazarek) shows a desk for use with electronic equipment wherein a structural part of the desk allows electrical power and data cords to be passed through them; 2,893,533 (Childs) deals with physical security and describes a cabinet having a portion with a typewriter, which, when not in use, is covered by a panel to produce a horizontal surface that may be used as a desk; U.S. Pat. No. 4,313,149 (Hirose, et al.) shows cabinets for containing electronic equipment which are arranged in an overlapping manner to permit interconnecting electronic cables to pass through the overlapped portions; U.S. Pat. No. 4,094,256 (Holper, et al.) shows a work table having supports with channels therein for receiving electrical wires.
None of these patents even remotely suggests a solution to the problem of the excessive cost and time required to physically and electronically secure a room which contains electronic equipment dealing with data desired to be maintained secret.